The present invention relates to a video camera, photo-camera and camera-system having light emission means such as a strobe which illuminates an foreground object (in short, object) with light emitted.
Using a video camera permits both a dynamic image and a still image to be obtained. It may be thought to use a strobe so as to provide adequate charge accumulation in an image pick-up device when light from an foreground object (in short, object light) is insufficient to photograph a still picture.
In the meantime, in a case where an image pick-up device having an electronic shutter function is used under the condition that an amount of strobe light is constant, the level of the image picked-up signal output is subject to be reduced with a shorter charge accumulation time and a smaller amount of charge accumulation as shutter speed is less shortened.
There is an idea that if object light is insufficient strobe light emission may automatically be carried out by detecting the level of the image picked-up signal and recognizing an amount of object light. In the idea above, for example, in a case when a person or thing in such a back light that substantially raises an level of an image picked-up signal is to be picked up; if an level of whole picked-up image signal is to be merely detected as a representative amount of object light, strobe light may not be emitted because the light on object is recognized to be sufficient. Consequently, the person or thing in the back light is subject to be picked up without a sufficient amount of object light.
In the meantime, in a case where a photo-camera (film-camera) is used, a strobe is generally utilized when object light is insufficient. Some of photo-cameras (film-cameras), having a means that an amount of object light is detected by an optical sensor such as a photo-diode so that strobe light emission is automatically carried out when object light is insufficient, have heretofore been well known.
If an optical sensor is used as a detector, however, an level of whole picked-up image signal is to be detected as a representative amount of object light. Accordingly, in a case when a person or thing in a back light is to be picked up, strobe light may not be emitted because of being recognized that amount of light from the object is sufficient. Therefore, the person or thing in a back light is subject to be picked up without a sufficient amount of object light.
Meanwhile, in a case when a strobe is used on a video camera so as to provide adequate charge accumulation in an image pick-up device, a shutter needs to be operated with depression of the button after the strobe is fully charged over a threshold value of voltage and ready to emit strobe light.
Further, great light due to strobe light emission is incident on the image pick-up device when a strobe is used. For this reason, the use of strobe may result in the saturation of charge accumulated in the image pick-up device.
On the other hand, a still-video camera which permits a picked-up image signal to sufficiently increase by compensating the loss of object light with strobe light emission has heretofore been proposed. This proposal teaches that amount of strobe light emission and charge accumulation time in an image pick-up device are determined and controlled in accordance with amount of object light detected by an optical sensor. In that conventional case, however, it has been a disadvantage of high purchase price level regarding a set of still-video camera that an optical sensor is needed to detect object light